Chemical Affinity in terms of Electromotive Force. 295 





Effect of halving the area of the zinc plate. 



Current, 

 in micro- 



Larger copper plate opposed. 



Smaller copper plate opposed. 



Mean 

 differ- 















amperes. 



T (1) 



.Larger 



(4) 



Smaller 



Differ- 



(2) 



Larger 



(3) 



Smaller 



Differ- 



ence. 





zinc' 



zmc. 





zmc. 



zinc. 







100 



1-082 



1-076 



•006 



1-078 



1-073 



•005 



•0055 



200 



1-071 



1-064 



•007 



1-066 



1-060 



•006 



•0065 



500 



1-061 



1-052 



•009 



1-055 



1047 



•008 



•0085 



1,000 



1-045 



1-035 



•010 



1-036 



1-026 



•010 



•0100 



2,000 



1-026 



1-011 



•013 



1-015 



•999 



•016 



•0145 



5,000 



•964 



•950 



•014 



•947 



•929 



•018 



•0160 



10,000 



•876 



•854 



•022 



•843 



■820 



•023 



•0225 



20,000 



•729 



■698 



■031 



•672 



•639 



•033 



•0320 



116. In precisely the same way, the following mean differ- 

 ence-values were obtained in two other analogous experiments, 

 in the first of which the zinc plates were amalgamated and 

 immersed in zinc-sulphate solution sp. gr. 1*42, the copper 

 plates being also amalgamated and immersed in copper- 

 sulphate solution sp. gr. 1*175; and in the second of which 

 electro-copper plates and copper-sulphate solution sp. gr. 

 1*175 were employed, conjoined wdth amalgamated zinc plates 

 immersed in dilute sulphuric acid sp. gr. T045. The above 

 mean difference-values are also exhibited in the table. 



Amalgamated zinc 



Amalgamated zinc 

 and electro-copper 



Bright zinc and 



and amalgamated 



electro-copper— 



| copper — zinc sul- 



— dilute sulphuric 



zinc-sulphate 



Ourrent, 



phate solution. 



acid. 



solution. 



m micro- 









amperes. 



Effect of halving 



Effect of halving- 



Effect of halving 





area of 



area of 



area of 





Copper. 



Zinc. 



Copper. 



Zinc. 



Copper. 



Zinc. 



100 



•001 



•001 



•001 



•001 



•0035 



•0055 



200 



•004 



•002 



•002 



•003 



•0045 



•0065 



500 



•009 



•003 



•003 



•005 



•0055 



•0085 



1,000 



•015 



•004 



•005 



•007 



•0090 



•0100 



2,000 



•024 



•005 



■011 



•010 



•0115 



•0145 



5,000 



•040 



•009 



•020 



•015 



•0190 



•0160 



10,000 



•049 



•017 



■041 



•020 



■0335 



•0225 



20,000 



•058 



•026 



•056 



•032 



•0580 



■0320 



Much the same kind of result was obtained in various 



other similar experiments ; the effect of halving the area of 



the copper plate was, especially with the stronger currents, 



much more marked than that of halving the area of the zinc 



2A2 



