404 



layer became more basic tliat is to say the normal inner equilibrium 

 tended to be established. 



Anoliier phenomenon showed by Beck which has not yet l)een 

 considered is tliat the potential of Mg in MgSO< solutions alone 

 becomes more negative as the concenti'alion increases. 



Up to the present it lias always been observed thai a metal dipped 

 into dilute solutions of the corresponding sulphates or chlorides were 

 more early disturbed than in concentrated solutions of the same salts. 

 This was particularly the case with sulphates but also with chlori- 

 des; the phenomenon was namely with chlorides also very distinct, 

 I hough not so strong as in the case of sulphates. 



This was always ascribed to (he strong catalytic effect of CI ions 

 and the less one of the SO,. Beck's measurements now show us 

 ihat with magnesium not in inner equilibrium, SO^ ions has also 

 a powerful effect. 



Although the highest potential shown in the last table ( — 1.8J6V) 

 is that of an active state of magnesium and the coexisting hydrogen 

 must have been in a strong stale of formation (strong overvoltage) 

 yet this potential of iVJg does not correspond with the inner eqnili- 

 lirium, for Mg containing small quantition of mercury shows a still 

 higher negative voltage. This value was a maximum for 2 at 



nvc Hg. 



Now Beck found thai the compound between Mg and Hg richest 

 in llie latter is Hg,Hg and Ihat the electrolytes in equilibrium with 

 the various amalgams are practically free from mercury. 



The influence therefore of the small quantity of mercury, under 

 discussion on the Mg electrode can only he an activating one for 

 the E— X tig. on the Mg side must be as follows (fig. 4). From 

 this will be seen Ihat if^the influence of small (|uantition of mercury 

 has not an activating one, then the potential of the amalgamated 

 magnesium would have been le.ss negative than that of the pure metal. 



Thus activating by small quantities of mercury causes the true 

 inner equilibrium to be approached more closely. 



Magnesium which has been activated by mercury showed a poten- 

 tial of — 1.856 Volts when placed in a solution containing 1 gr. 

 mol. of MgSO, per liter. 



Even this potential is below the equilibrium value owing to the 

 disturbing effect, due to corrosion, but it is probable this is near 

 I he true equilibrium potential. 



If is evident, that the potential of pure magnesium in true inner 

 e(|nilibrium must be more negative than that of the not disturbed 

 amalgam, containing 2 at V« Hg., because the E — X diagram 



