upon Electric Discharge, 273 



light falling upon the body aid the passage of the electricity 

 from that body into the atmosphere, in my experiments such 

 setherial vibrations are generated by the electrode -flames 

 themselves, or in case of electrode-points are caused by electric 

 lights which are always formed at the extremities of the 

 points. 



Consequently, in such cases as those I mention, in tlie elec- 

 trodes themselves are found the conditions favourable to the 

 passage of electricity from the electrodes to the air, as is 

 proved by the above experiments. According to all pro- 

 bability, on the limits separating the air from the body charged 

 with electricity appears a particular polarization as presumed 

 by Edlund. The setherial vibrations of light weaken this 

 polarization, I. e. the energy of light in this case favours the 

 formation of the current. Something almost similar to this 

 we have perhaps in the phenomena called photo-electric. 



I repeated the experiments of Hallwachs with a zinc disk 

 charged with negative electricity, and found that under the 

 influence of electric light the diminution of the potential upon 

 the disk is accomplished unequally. At the beginning of the 

 illuminating the loss of the charge takes place much slower 

 than afterwards, i. e. the longer the disk remains illuminated 

 the quicker is accomplished the diminution of its potential. 

 Some experiments even show that an after-action of the light 

 is observed. 



I also made the following experiment : — An electric regu- 

 lator was removed to a considerable distance from the zinc 

 disk, and the electric light was weak. When the disk was 

 illuminated no diminution of the potential on it was visible, 

 even when a zinc screen, perforated for the passage of the 

 light, was placed very near the disk. I removed the screen 

 and in its stead I placed before the disk a Bunsen's flame in 

 contact with the earth, and at such a distance that it could 

 have no influence on the charge of the disk. As soon as the 

 regulator was opened and the light thrown upon the disk, 

 the diminution of the potential of the disk immediately began, 

 i. e. a current icas established between the disk and the flame. 

 Thus the use of a flame as one electrode favorises the crea- 

 tion of a current through the air when a charged zinc disk 

 standing as the opposite electrode is illuminated. 



St. Petersburg, Yours truly, 



May 18, 1888. Dr. J. BORGMANN. 



Phil. Mag. S. 5. Vol. 26. No. 160. Sept. 1888. 



