IN AQUEOUS SOLUTION, AND TEIE EXISTENCE OF CO^IPLEX IONS. 
117 
o-oj 
Jig. .3. 
likely to arise, the ratio of the areas of the tnlies lieiiig approximately 1, : Do, 
In this apparatus, as in that shown, tig. 2, the electrode cells, instead of being 
ground into the tubes, are connected by means of thick rubber 
tubing ; the tube G serves as a handle by which the apparatus 
may be held in a clamp, and also, like E in figs. 1 and 2, to 
allow for expansion of the liquid. 
The apparatus shown in the figure permits of the use of the 
following combinations : The tubes A and B may be used in 
three ways : with two cells similar to D both indicators may 
be placed on top ; with one vessel, D, and one E, as shown in 
the figure, one indicator may be used from above and one from 
underneath ; and with two vessels such as E both indicat(3rs 
from underneath. The same combination may be employed v/ith 
the tubes B and C, whereas with A and C the apparatus can be 
used only in the second of these three manners ; by the use of a 
second similar apparatus in which the tube C is replaced by B, 
and vice versd. All jiossible combinations of these three tubes, 
two at a time, may be obtained. 
V 
For the calculation of — from the observed velocity, since 
the latter is proportional to the potential fall, and this inversely 
as the sectional area of the tubes, it is only necessary to multiply 
the velocity of the boundary in one tube by the ratio of tlie two 
areas. Thus, using the tubes A and C, the sectional areas of which are a and y, if 
U' and V' are the actually observed velocities of the two margins, the ratio of the 
ionic velocities is given by 
U 
Y 
7 IF 
In Table L are given the potential falls whicli have been found to give a measure- 
able boundary in the case of thirty-eight different pairs of solutions. In addition to 
those tabulated, the following have also been examined, but no good margins could be 
obtained : 
H 
NO., 
H 
NO3 ’ 
NO., \ Ou 
Li ’ 
U 
Mg 
Cl, ^ci 
JLl 
Li 
Chi 
Cl, 
and cadmium chloride as indicator following 2N solutions of the chlorides of potas¬ 
sium, lithium, magnesium, and calcium. 
In the first column of the table is given the system forming tlie boundary, thus ; 
K — represents the boundary between an acetate and a chloride whose common 
