( 100 ) 
On the bottom of the right limb is placed 
a 10% zinc amalgam and in the left limb 
a weighed amount of pure mercury. The 
whole is filled up with a solution of zinc 
sulphate not saturated at 0°5 (its reaction 
was perfectly neutral towards congo-red). 
I and I are two rods of chemically pure 
zinc which are in communication with th$ 
polar terminals Zn, and Zn„ while P, and P, 
lead to the mercury and the 10% amalgam 
respectively. The apparatus is placed in a 
thermostat (0°.5) and, Zn, and P, are now 
put in a circuit, in which is placed an 
accumulator with a resistance coil, in such 
a manner that on closing the same Zn, 
acts as anode and P, as cathode. A certain 
amount of metallic zinc is then precipitated 
from the zinc sulphate solution which dis¬ 
solves in the mercury and so yields an 
amalgam. In that circuit we also put a milliamperemeter; so if 
the time which the current has passed is known, the concentration 
of the amalgam formed will be accurately known. Our milliampere¬ 
meter was carefully checked by means of a silver coulometer, but 
by way of control we also put in during the experiment two 
silver coulometers besides the milliamperemeter. 
If, now (by means of a swing) P,P 2 or Zn,P 2 , respectively, is 
introduced into the potentiometer of Poggendorff — du Bois-Reymond, 
the E.M.F. between the 10% zinc amalgam and the #-% amalgams 
formed may be measured at any moment, and also that between 
pure zinc (in rod shape) and the 10°/ 0 amalgam. 
Before each measurement the whole cell was shaken vigorously in 
order to stir up the zinc solution (whose concentration might change 
locally in consequence of the electrolysis) and also the amalgam. 
5. Whereas for the sake of brevity we omit the description of 
these measurements and of the controlled apparatus employed we give 
in the following tables the results of our measurements. It should 
be stated that all the experiments were made in duplicate. 
As required by theory the lu% amalgam forms at all concentrations 
where there is still an E.M.F. the negative (solution pole). The 
second and third column show how little defined is the potential of 
pure zinc- the rods Zn, and Zn, were two halves of the same rod. 
