Charged Bodies at Moderate Temperatures, 449 



§ 11. Experiments of a similar nature were made with a 

 number of other substances. It was found that with potas- 

 sium chloride on which iodine had been sprinkled, spread on 

 zinc strips and insulated on the iron plates in the iron box, no 

 increased leakage of either positive or of negative charges 

 was produced on heating. With bromine instead of iodine 

 an increased leak was obtained, which, however, was not 

 steady. There was no definite position to which the electro- 

 meter-reading tended when the zinc strips were insulated 

 without charge. 



The electrometer-reading was sometimes on the positive 

 side of the metallic zero, sometimes on the negative. The 

 effect ceased after heating for about half an hour. A crack- 

 ling noise accompanied the heating, and solid particles were 

 thrown off the insulated zinc strips on to the iron box. 



With zinc chloride spread on insulated iron plates, it was 

 found that on heating there was for each experiment a defi- 

 nite reading, sometimes on the positive, at other times on the 

 negative side of the metallic zero, to which the electrometer- 

 reading deviated on heat being applied to the outside of the 

 box. 



In the following list the results of the various experiments, 

 where the quadrant-electrometer was used, are tabulated : — 







! 



i 

 Difference of 





Outside box- 

 connected 

 to case 



Insulated 



plates 

 made of: 



Substance 

 used. 



potential ob- 

 Substances served when no 

 placed on : charge given and 



Remarks. 



made of: 





temperature 

 raised to about 



















350° C. 





iron. 



iron. 



Sodium chlor- 



zinc strips on None. 









ide. 



insulated iron 

 plates. 







iron. 



iron. 



Sodium chlor- 



Negative. 



Steady. 







ide with io- 













dine; 









iron. 



iron. 



»» 



zinc strips on Positive, 

 disinsulated 

 iron box. 



j> 



zinc. 



copper. 



" 



zinc strips on Positive, 

 disinsulated 

 zinc box. 



" 



iron. 



iron. 



Sodium chlor- 

 ide with bro- 

 mine. 



zinc strips on ; Negative, 

 insulated iron 

 plates. 



)■> 



iron. 



iron. 



Lithium chlor- 

 ide with io- 

 dine or with 

 bromine. 



zinc strips on Negative, 

 insulated iron ' 

 plates. 



>» 



iron. 



iron. 



Zinc chloride. 



iron plates. ' Negative. 



1 



" 



