Mr. J. B. Henderson. Polarisation of 

 Fio. 3. 



[June 15, 



QUADRANT ELECTROMETER 



BATTERY 



The order of an experiment was the following. 



After carefully standardising the electrometer, the electrolysis 

 was started, and the unearthed electrode connected by a wire (not 

 shown in the diagram) to the unearthed quadrants. The deflec- 

 tion of the needle thus produced, which showed the difference of 

 potential between the electrodes, continued to increase steadily until, 

 after the lapse of an interval of time depending on the strength of 

 the current, it became constant. When this stage was reached, the 

 wire mentioned above was removed and the key k' pressed and kept 

 down, thus making connexion between the slider and the quadrants. 

 The slider was then moved along until the deflection was nearly 

 equal to that which would be given by the polarisation, and the 

 key & momentarily pressed, thereby breaking the current circuit and 

 connecting the electrode to the quadrants. An impulsive deflection 

 immediately followed, unless the potential of the quadrants was 

 equal to that of polarisation. If this, deflection was negative (which 

 indicated that the potential of polarisation was less than that of the 

 quadrants) the slider was moved so as to reduce the potential of the 

 quadrants below that of polarisation, thereby making the impulsive 



