Charged Bodies at Moderate Temperatures. 103 



When the potassium bichromate was taken out and the 

 zinc plates cleaned and heat applied to the insulated zinc 

 plates with nothing on them, there was no increased leak. 



In the opposite figure the leak is represented graphically 

 with time as abscissa and current as ordinate. The units are 

 the minute and ^ microampere respectively. Dotted lines 

 denote results obtained with flame lit. 



The experiments with zinc plates insulated in the iron box 

 with potassium bichromate and iodine were varied in the 

 following manner : — On the bottom of the iron box a strip of 

 iron with potassium bichromate spread over it was placed. 

 Nothing was put on the insulated zinc plates. When heat 

 was applied, no increased leak was obtained. When iodine 

 was sprinkled over the potassium bichromate and heat applied, 

 the same increased leak was observed as has been already 

 mentioned when the potassium bichromate sprinkled with 

 iodine was placed on the insulated zinc plates and heat 

 applied. This increased rate of leak on heating was also 

 obtained when potassium bichromate which had once been 

 sprinkled with iodine and then heated was a second time 

 heated after being laid aside for a day ; no new supply of iodine 

 being applied in this second case. 



No increased rate of leak was observed when pieces of 

 sodium were placed on the insulated zinc plates when heat 

 was applied. 



Similarly, when common salt was spread over the insulated 

 zinc plates and these were charged and heat applied, no 

 increased leak was observed. 



With common salt spread over the zinc plates and iodine 

 sprinkled over that, an increased leak was observed after a 

 few minutes' heating. If the salt was allowed to stay for 

 a week or more on the zinc plates on which it had been 

 originally used, and after that time again heated, the increased 

 leak was again observed, even without a second sprinkling 

 of iodine. 



Table showing results with common salt alone and with common 

 salt and iodine spread over the insulated zinc plates. 



21st Nov., 1898. 



Zinc plates alone. . 



Zinc plates and 1 

 common salt ... J* 



Zinc plates with | 

 common salt and | 

 iodine sprinkled f 

 over it | 



Charged to 

 + 211 volts. 



+ 185 „ 

 + 177 „ 











Microamp. 







Drop of 





per min. 



No flame. 



15 i 



•olts in 5 



mins. 



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51-5 



„ ,, 20 





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9 



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•00000057 



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50 



„ „ 15 





•00000063 



No 



11 



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15-5 



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40-5 



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, 



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60 



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min. 



■00001140 



