(ED) 
which can exist together at 188°, are situated at lower temperatures 
on the lines KF and DG, we then have at 25° d and e as limits 
and all the percentages between these are again heterogeneous and 
consists of both the mixed erystals d and e. On the other hand we 
have again from e—f a series of homogeneous mixed erystals ending 
with pure cadmium. 
The line indicated in fig. 2 shows the # M F of the cells described 
in which the negative pole consists of the whole series of the amal- 
gams in succession. The letters correspond with those in fig. 1. It 
therefore appears, that as long as we are dealing with a series of 
amalgams consisting of one phase (ab, cd, ef) whether liquid (ab) 
or solid (cd and ef) the H. MF varies regularly with the concen- 
tration of the amalgam. On the other hand we have in two cases a 
constant / MF accompanying variable concentration, namely from 
b to ce and from d to e. In the first case it corresponds with the 
fact that the amalgam is a two-phased one (liquid 5 and solid c): 
in the second it must, therefore be also two-phased, but both phases 
are now solid mixed crystals (d ande). In this manner the limits 
of the horizontal part de could be determined for different temperatures. 
From this it was found that on cooling below [88° the limits diverge 
still further until at 25° they have become: 65 and 80 atoms of 
cadmium percent. 
The horizontal line be is of great significance for the WESTON- 
cells. We can now see plainly why a cell of constant # M F may 
be easily constructed if only the percentage of the amalgam which 
serves as negative pole is chosen somewhere on this line. We then 
have an amalgam which is partiy liquid and partly solid. Such a 
mass usually attains equilibrium quickly and sharply when the 
temperature is changed. Moreover, the composition of the alloy 
remains on the line for a considerable time even though the total 
amount of cadmium decreases by the action of the current. This 
merely causes a slight diminution in the amount of mixed crystals 
and an increase in the volume of the liquid but the composition 
of both and consequently the # M F remains constant. 
The extremities of the line be alter, however, their position with 
the temperature as shown in fig. 1. This was noticed most plainly 
when determining the HM F: the positions of the points b and ¢ 
thus found correspond exactly with those in fig. 1. 
The many irregularities which have been observed when using 
Wesron-cells may be easily explained by the fact that up to the 
present an amalgam has been used containing too large a proportion 
of cadmium, too near to point c, so that on cooling one soon got outside 
