; 
6 Messrs Paine and Evans, The Conductivity of 4 
thoroughly cleaned; the water in which they stood was renewed 
twice a day for three days. The glass caps were treated in the 
same manner. 
Again, when transferring a solution from one vessel to another, 
a small quantity was always poured away first of all, for the 
purpose of washing that part of the lip over which the liquid 
flows. 
In order to determine what sort of error was possible through 
the transference of such extremely dilute solutions to the con- | 
ductivity cell, three or four samples of water were taken | 
successively from the same flask, and their resistances measured. | 
Series of readings of this nature were made from time to time | 
with different specimens of distilled water. The following four — 
series will serve as examples. The readings are in ohms. 
I II Ill IV 
710,000 690,000 541,000 1,570,000 
664,000 650,000 592,000 1,510,000 
717,000 665,000 640,500 1,500,000 
592,000 1,600,000 
‘These resistances show no continuous decrease. Variations in | 
the readings certainly occur, but the fluctuations are irregular, 
and there is no distinct evidence that the water in the flask was | 
fouled through the opening of the flask on these occasions. The - 
fouling, where it occurs, is rather in that portion of the water that 
flows out into the conductivity cell. 
Errors of this nature, it will be noticed, would have the effect 
of introducing irregularity amongst the individual readings of 
resistances, but would not appreciably alter the general direction | 
of the conductivity curve plotted in the manner already | 
described. 
There was an effect other than fouling, however, which proved 
of far more serious consequence, namely, what seemed to be ad- — 
sorption on the surfaces of the glass vessels. For these very 
dilute solutions this could not be ignored. In the case of the acid 
solutions it was apparently negligible, but in that of the alkali — 
solutions it rendered the results of little value. Thus the con-_ 
ductivity of the very dilute alkali solutions gradually diminished, ~ 
while the conductivity of pure water subsequently introduced into — 
the vessel gradually increased. Consequently only the sulphuric ~ 
acid results are recorded. 
III. 
The following, Table I, is a sample of the series of experiments — 
performed. It contains the measurements made on a series of 
sulphuric acid solutions prepared with one specimen of distilled 
water. The cell constant (4) = 0°550. 
