Prof. Franz Exner an Contact Electricity. 



289 



II. Experiments with Copper ancl Platinum. Mode of 

 observation and arrangement f table same as before. 



1 



A. 



B. 



0. 



D. 



E. 



F. 



a. 



1. 



N=679 

 a =729 



N=679 #=32 

 a=565 ! D=82 



N=680 

 a = 649 



# =31 



a?=31-5 



#=•38 



2. 



N=681 

 a =735 



N=681 

 a =565 



a?=31 



D=85 



N = 680 

 a =649 



#=31 



a? =31 



#=•35 



3. 



N=701 

 a =750 



N=701 

 a =592 



#=30 

 D=79 



N=703 

 «=672 



a?=3I 



a? =30-5 



#=•39 



4. 



N=709 

 «=770 



N=709 



a =575 



a- =36-5 

 D=97'5 



N=709 

 a =672-5 



#=36-5 



a? =36-5 



#=•37 



5. 



N=709 

 a =768 



N=709 

 a=577 



# =36-5 

 D=955 



N=709-5 

 a = 674 



x =35-5 



#=36 



# = •38 



6. 



N=707 

 a =769 



N=707 

 a=577 



#=34 

 D=96 



N=707 

 a =673 



#=34 



#=34 



#=•35 



7. 



N=708 

 «=770 



N=708 

 a =578 



#=34 

 D=96 



N=708 

 a = 674 



a:=34 



x =34 



# = •35 













Mean.. 



. #=-367 



These experiments do not agree with one another so well 

 as those with zinc. I have generally found that, of all metals, 

 zinc gives by far the most constant results. The heat of oxi- 

 dation of copper is, according to Thomsen, 18,600 calories; and 

 from this is calculated as above the value of Cu | Pt='383 

 Daniell, which agrees sufficiently well with experiment. 



The fact that in different experiments the absolute values 

 for x and D are not quite equal is because between almost 

 every two experiments the paraffin layer was either completely 

 melted or, at all events, gone over with a Bunsen flame. 



III. Experiments with Iron and Platinum. Method of obser- 

 vation and arrangement of table same as in I. and II. With 

 iron especial caution is required, and it is imperatively neces- 

 sary that the plates be newly cleaned before every experiment. 





A. 



B. 



O. 



D. 



E. 



F. 



G. 



1. 



N=800 

 «=812 



N=800 

 a =720 



#=34 

 D=46 



N=800 

 a = 766 



# = 34 



#=34 



x =*75 



2. 



N=822 

 a =834 



N=820 

 a =741 



#=335 

 D=45-5 



N = 820 

 a = 787 



# = 33 



#=332 



#=•73 



3. 



N=795 

 a=810 



N=790 

 a = 713 



#=31 

 D=46 



N=790 

 a =759 



# = 31 



#=31 



# = ■68 



4. 



N=830 

 a =844 



N=830 

 a =746 



#=35 

 D=49 



N=830 

 a=795 



# = 35 



# = 35 



# = •71 



5. 



N=758 

 a=772 



N=758 

 a =680 



# = 32 

 D = 46 



N=760 

 a =729 



#=31 



# = 31-5 



#=•68 



6. 



N=712 

 a=727 



N=712 

 a=627 



#=35 

 D=50 



N=715 



«=680 



# = 35 



# = 35 



# = •70 



7. 



N=681 

 a =699 



N = 682 

 a =586 



#=39 

 D=57 



N=680 

 a=641 



#=39 



# = 39 



# = •68 



8. 



N=698 

 a=713 



N=699 



«=613 



.r=35-5 

 D=506 



N=700 



a = 665 



#=35 



#=35'2 



#=•70 















Mfinn 



.7 71 u 



