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Prof. A. Schuster. On the 



[June 16, 



A cylindrical glass vessel, 38 cm. high and 15 cm. wide, was 

 divided into two approximately equal compartments by a vertical 

 metallic screen. There was an open space of about 5 mm. between 

 the screen and the sides of the vessel, a space about 4 cm. above, and 

 2'5 cm. below the screen. One compartment contained two pieces of 

 gold leaf, which could be charged from the outside. The other 

 compartment contained two electrodes about 5 cm. apart, and 2 cm. 

 from the screen ; these distances could be varied during the experi- 

 ment. The screen was always conducted to earth, and the electric 

 fields on the two sides of the screen were therefore nearly independent 

 of each other. When the gold leaves were electrified and divergent, 

 and discharges from the induction coil passed between the electrodes 

 on the other side, no effect could be observed at atmospheric pressure : 

 the gold leaves remained divergent. 



At a pressure of about 4*3 cm. of mercury, the effect I was looking 

 for first appeared ; when the discharge passed, the divergent leaves 

 slowly collapsed, and as the pressure was further diminished the 

 collapse took place more and more quickly. 



We have here then even with the discontinuous discharge a neutra- 

 lisation of all normal forces at the surface of the gold leaf. 



Fig. 1 illustrates in a diagrammatic form the arrangement of the 

 experiment, A and B being the electrodes, S the screen conducted to 

 earth, and E the gold leaf. 



Fig. 1. 



In previous experiments, which were not so satisfactory from 

 another point of view, and which I therefore do not quote, the same 

 effects were observed both with the continuous currents from the 

 battery and the discharges from the coil ; the only difference being, 

 that the effects due to the continuous discharge were more rapid and 

 regular than those due to the induction coil. As soon as the pressure 

 was sufficiently reduced to allow the continuous discharge to pass, the 

 destruction of normal forces took place. 



It seemed to me to be interesting to observe more particularly the 



