1887.] Mr W. Peddie on Electrolytic Polarization. 
109 
I have adopted, as a better approximation to the law connecting 
current-strength and time, the equation 
. 7 ci - kt 
i = a + be ^ 
The curve represented by this equation does not differ much from 
that represented by the equation formerly given. It possesses to a 
certain extent symmetry about an axis. In fig. 3 I have represented 
a group of curves having this equation, passing through a given 
point on the axis of i, and having a common asymptote. The curves 
which pass to tbe left of the axis of i cannot, of course, represent 
the physical phenomena, but they show the axial symmetry well. 
If another group is drawn, the axis of i being a tangent, and each 
member having a different horizontal asymptote, a close resemblance 
between it and the group in fig. 2 is evident. 
If equation (1) holds, we have 
log (i ~-a) — ci = log b — kt . . . . (2). 
Hence the quantity on the left-hand side of this equation plotted 
against time should give a straight line. The group of points in 
fig. 1 is obtained in this way from the curve in that figure. The 
near coincidence of all the points with a straight line shows that 
the curve is closely represented by an equation of the form (1). 
I have also made an experiment with only one tray-Daniell cell 
in the circuit. There was, consequently, no decomposition of the 
electrolyte (an aqueous solution of sulphuric acid). In this case the 
constant a must be zero. The equation 
• n a mo l‘092t -0-40154 
^ = 0•4168e 
represents the results of observation almost exactly, the difference 
being well within the limit of possible errors in drawing the curve 
free-hand through the observed points. For small values of t there 
is considerable discrepancy between the results of observation and 
calculation in both experiments, so that the formula (1) must not 
be applied when t is below a certain limit, which, for the results 
tabulated above, is about 5 minutes. 
