the Electrical Conduction produced by it. 149 



In the first method a thin wire or strip was placed between 

 two parallel plates one of which was covered with uranium. 

 The wire was connected with the electrometer, and after being 

 left some time took up the potential in the air close to the 

 wire. In the second method the ordinary mercury- or 

 water-dropper was employed to measure the potential at a 

 point. 



For the first method two large zinc plates were taken 

 and placed horizontal and parallel to one another. A layer 

 of uranium oxide was spread over the lower plate. The 

 bottom plate was connected to one pole of a battery of 8 volts, 

 and the top plate was connected to earth. An insulated thin 

 zinc strip was placed between the plates and parallel to 

 them. The strip was connected with the electrometer, and 

 gradually took up the potential of the point. By moving 

 the strip the potential at different points between the plates 

 could be determined. 



The following table is an example of the results obtained. 



Plates 4' 8 cm. apart ; 8 volts between plates. 



Distance from 

 top plate. 



Potential in 



volts 



with Uranium. 



Potential in volts 



without 



Uranium. 





 •6 

 1-2 

 2-1 

 3-1 

 4-8 





 25 



3-8 

 5-9 



7 

 8 





 1 



2 



35 



5-2 



8 



The third column is calculated on the assumption that without 

 the uranium the potential falls off uniformly between the 

 plates. 



The method given above is not very satisfactory when the 

 strip is close to the plates, as it takes up the potential of the 

 point very slowly. 



The water- or mercury-dropper was more rapid in its 

 action, and gave results very similar to those obtained by the 

 first method. Two parallel brass plates were placed vertically 

 and insulated. One plate was connected to the positive and 



