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XX. Note on the. Measurement of the Electric Resistance of 
Liquids. By Professors W. E. Ayrton, F.R.S.,and John 
Perry. M.E.* 
[Plate II.] 
SOME time back a paper was communicated by Prof. 
Eeinold to this Society on the Resistance of Liquid 
Films, which had a double interest, arising from the great 
value of the results arrived at and from the method employed 
to obtain them. It is of course well known that the great 
difficulty in measuring the resistance of a liquid arises from 
the polarization of, or actual deposit of gases on, the anode 
and cathode, which makes the apparent resistance of the liquid 
far greater than the true value. To overcome this difficulty 
Kohlrausch employed rapidly alternating currents; and Dr. 
Guthrie, with Mr. Boys, dispensed altogether with the anode 
and cathode by observing the amount of twist produced in a 
fine steel wire supporting a vessel of liquid when a magnet 
was rotated at a fixed speed in the neighbourhood. 
But there is another method of measuring the resistance of 
a liquid independently of its polarization — the one so success- 
fully employed by Prof. Eeinold, and which consists in 
measuring by means of an electrometer the potential-difference 
at two fixed points in a column of the liquid when a current 
of known strength is passing through it. 
At the time Prof. Remold communicated his paper, we 
mentioned that some years previously certain experiments had 
been conducted in our laboratory in Japan for the purpose of 
ascertaining how far the electrometer method of measuring 
the resistance of a liquid was entirely independent of polari- 
zation; and as we have since come across the results of these 
experiments in turning over some papers, we have thought 
that the information may possess some interest for the Mem- 
bers of this Society. The experiments were made at the com- 
mencement of 1878 by some of our students; and the first 
part of the investigation was for the purpose of ascertaining 
how the resistance of water varied with the electromotive force 
employed and with the temperature of the water when, first, 
the resistance was measured by the current which a known 
electromotive force could send between platinum plates of 
known size and at fixed distances apart in the water, and, 
secondly, when the resistance was measured by a comparison 
of the potential-differences of two platinum wires placed in 
the water at fixed distances apart, with the potential-differ- 
* Communicated by the Physical Society, having been read June 9, 
1883. 
