1883.] Electric Discharge with Chloride of Silver Battery. 299 



condition of the discharge itself within the tube. It is certainly very 

 remarkable that while the potential of the negative ring was abso- 

 lutely zero, a high negative potential should be developed in its near 

 vicinity. 



The authors remark that everyone familiar with the appearance of a 

 stratified discharge will have noticed when the negative terminal is a 

 ring, that as the exhaust proceeds a spindle of light approaches, and 

 at last protrudes through the interior of it (fig. 11, 1, 2, 3, 4, 5) ; 

 this spindle they regard as a visible exponent of strong action among 

 the molecules of gas composing it. In order to probe its electrical con- 

 dition, they prepared a tube with a central idle wire, surrounded by a 

 minute glass tube, except its extremity, and projecting to a distance 

 of f inch (0*95 centim.) from the plane of the ring, which was made 

 negative. Another idle wire was sealed in the tube 0'15 inch (0'38 

 centim.), from the periphery of the ring. As the exhaust proceeded 



Fig. 11. 









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MB 









i d mm* mm n 



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with a charge of carbonic anhydride, the spindle approached the 

 ring, and ultimately protruded through it. It was found that the 

 potential of the central idle wire increased with the exhaust, until 

 it nearly or quite equalled that of the whole tube ; while that of 

 the external idle wire was only 0'054 that of the tube. 



A great number of experiments were made to test the potential 

 across a stratum a, ~b, and across a dark space c, d, respectively, by 



