104 Dr. J. C. Beattie on tlie Leakage of Electricity from 



It was found after the flame was extinguished and the 

 apparatus allowed to stand for ten minutes, that the normal 

 rate of leak again obtained. Finally the salt was removed 

 from the zinc plates, and these latter were again insulated in 

 the box with nothing on them, and heat applied: no increased 

 rate of leak was then observed. 



The same results were obtained again on the 24th and 25th 

 of November. The zinc plates were then laid aside with the 

 salt on them, until the 1st of December. They were then 

 insulated in the iron box again, no additional iodine having 

 been spread over them : the same increased leak was obtained 

 on heating. The salt was then taken off, and the zinc plates 

 again insulated in the iron box. It was found that they no 

 longer insulated when heat was applied for some minutes. 

 It was only after they had been thoroughly cleaned that the 

 zinc plates with nothing on them were able to hold the 

 electricity when heat was applied. 



When the zinc plates were covered with lithium chloride, 

 and heat was applied, no increased leak took place: when, on 

 the other hand, the lithium chloride was sprinkled with iodine 

 the drop of potential increased to 40 or 50 volts per minute 

 after a few minutes' heating. 



No increased fall of potential was observed if the zinc 

 plates were covered with potassium bromide sprinkled or not 

 sprinkled with iodine, when heat was applied. 



The effect on heating when the plates were covered with 

 potassium chloride was doubtful; the increase not being more 

 than 1 volt per minute after 20 minutes' heating. 



With potassium iodide on the zinc plates an increased fall 

 of potential was observed when the plates were heated for 

 the first time ; this fall was less on the second time of 

 heating. 



With potassium nitrate no increased leak was observed 

 after heating for almost an hour and a half. The charge 

 given was sometimes positive, sometimes negative. 



When calcium sulphide or barium sulphide was spread 

 over the insulated zinc plates, no increased drop of potential 

 was obtained on applying the flame ; with iodine sprinkled 

 over these substances heating produced no increased drop of 

 potential. 



On the other hand, a very pronounced increase of leak was 

 produced when zinc sulphide was spread over the insulated 

 zinc plates, and heat was applied, and this without sprinkling 

 the zinc sulphide with iodine. It was found that after the 

 zinc sulphide was removed and the zinc plates again insulated 

 in the iron box ; the plates themselves showed increased 



