91 
value has been reached, is represented on the photo, Fig. 3. As the 
subsequent process is much slower, the velocity of revolution of the 
drum of the registering apparatus was chosen smaller here. We see 
that the potential remains constant for some time, and then proceeds 
to positive values with ever increasing rapidity. The initial point 
of this change coincides with the moment at which the grey mercury 
deposition makes room for the liquid shiny mercury phase. 
In a following communication we shall, among other things, state 
the results obtained when other aluminiums and mercuri-salt solutions 
were used. 
Laboratory of General and Anorganic 
Chemistry of the University. 
Amsterdam, May 8 1921. 
