572 
CHEMISTRY: E. IV. WASHBURN 
dropping into this cell small individual crystals of potassium chloride 
weighed out on an assay balance. In this way the conductivity data 
were carried down to 0.00002 normal. 
The values obtained are shown in figure 1 (A, CA curve), which is 
taken from the thesis of Dr. H. J. Weiland,^ to whose careful work the 
final success of the investigation has been largely due. In this figure 
are represented four independent series of experiments, through which 
the best representative curve is drawn. The small crosses show the 
values found by Kohlrausch and Maltby. 
In order to determine the value of Ao, and also the limiting value, 
Kq, of the mass-action expression as the concentration approached zero, 
it is necessary to extrapolate from 0.00002 normal. Of the various 
methods which have been employed for extrapolating conductivity 
data, those of Kohlrausch^ and of Noyes,^ as well as all others which 
are based upon the assumption that the electrolyte does not obey the 
Mass- Action Law within any concentration range must, it seems to the 
writer, be rejected because the known behavior of such electrolytes is 
entirely in harmony with obedience to the Mass-Action Law in suffi- 
ciently dilute solutions. Functions of the form 
which have been proposed and employed by Kraus and Bray^ must also 
be rejected, because, although in form they reduce to the Mass^Action 
Law when C = 0, they cannot as a matter of fact be made to represent 
the conductivity data in dilute solutions, being nothing more than 
empirical interpolation equations which will express approximately 
(0.1%) the variation of conductivity with concentration between 0.001 
and 2 normal. The recent function proposed by Bates, ^ log = 
/Ay 
log i^Q-f^MC^ I expresses very accurately the conductivity data for 
potassium chloride between 0.0001 normal (the lowest concentration 
reached by Kohlrausch) and 1 normal, but it also cannot be made to 
express the conductivity data below 0.0001 normal. Both the Kraus 
equation and the Bates equation fulfil the condition of obedience to the 
Mass-Action Law whenC = 0, but they both impose upon the electrolyte 
an arbitrary method of approach to the condition of constancy required 
by the Mass-Action Law. The two methods of approach are both radi- 
cally different and both wrong, since neither form of function can be 
fitted to the data in the most dilute solutions. In fact, any method of 
extrapolation which imposes an arbitrary a priori determined path by 
