686 



It follows from this table in the first place that addition of broinic 

 water makes the potential of the nickel rise at first by about 0,65 Volt. 

 Tiien a maximum is reached, after which a cousiderable decrease 

 takes place. We further see that wiien after the potential did not 

 change any more, the bromic concentration was raised to saturation 

 b}^ the addition of three drops of bromine, the potential of tiie Ni 

 changed only exceedingly little. 



This very remarbable result ^) led us to suspect that the distui-b- 

 ance of the internal equilibrium caused by the action of the bromine, 

 is catalytically influenced by Br'-ions which had arisen when the 

 metal was etched. With certain Br'-ion-concentration the positive cata- 

 lytic action of the Br'-ions is so great that it can just compensate the 

 disturbing action of the bromine, and the Br'-ion-concentration increasing 

 continually, a considerable decrease will then have to set in. If now 

 the bromine concentration is increased considerably, both the disturb- 

 ing action and the catalytic action is greatly increased, after which 

 the condition can become pretty well stationary, and addition of 

 more bromine has little or no influence. To test this supposition 

 the potential of the Ni was first carried up by bromine water, and 

 then KBr was added with the following result : 



Ni-electrode in 100 cm^ '/,(, Norm. Ni (N03)2-solution. 



We see from this that addition of KBr made the potential of Ni 

 really decrease greatly, but then it was necessary in order to get 

 more certainty about the signification of the phenomenon to examine 

 in how far Ni behaved here as a Bromine electrode. 



') The same result was obtained with a Nieleclrode glowed in vacuo, from 

 which follows that possibly dissolved hydrogen exerts no influence on the pheno- 

 menon. 



