89 
the aluminium cell is not yet closed, or what comes to the same 
thing, when the aluminium experimental electrode is immersed in 
the same pure aluminium sulphate solution in which the aluminium 
measuring electrode is placed. 
In 6 the experimental electrode was suddenly immersed in the 
solution of aluminium sulphate —+ sublimate. On being attacked 
the potential of the experimental electrode is immediately greatly 
disturbed. The amount of this disturbance may be inferred from 
the place of the gauging line, which corresponds with a potential 
difference of + 0.830 Volt. 
In consequence of the evidently strong catalytic action of the 
mercury dissolved in the metal surface, this disturbance not only 
rapidly diminished in c, but the ‘potential rises to a much more 
negative value than that of the aluminium in the initial state. This 
shows, therefore, that the aluminium has passed into a much less 
noble and more active state through the dissolved mercury, which 
means in other words that the mercury here enormously accelerates 
the conversion in the direction of the internal equilibrium, notwith- 
standing the fact that under the given circumstances this conversion 
is attended with a stronger attack. At e the potential reaches its 
most negative value, and remains there constant for some time. As 
the aluminium is here covered with finely divided mercury, which 
gives the electrode a greyish colour, this constant potential, when 
at least the same state prevails throughout the metal surface, cor- 
responds with the three-phase equilibrium c, s,/, i.e. with the 
heterogeneous equilibrium between 
the activated mercury-containing 
aluminium mixed erystal phase, 
at f the aluminium-containing liquid 
mercury phase, and the electro- 
lyte in the boundary layer. 
FE | Accordingly summarizing we 
may say that when we start from 
a potential at the same level as 
b the point p, this potential at first 
descends to a value at the level 
of e.g. point g. 
When activation has taken place, 
2 Âl IE 3H °° and the three-phase equilibrium 
1 has been established, the potential 
Fig. 2. is indicated by the line ¢, s, /, 
which lies much higher. In virtue of the mercury content of the 
