SURFACE TENSION OF AQUEOUS SOLUTIONS.—BARNES. 53 
These wires, and also those between the induction coil and 
the Wheatstone bridge, were run parallel and close together to 
diminish any effects from self-induction. 
Reduction Factor. 
The capacity of the electrolytic cell was obtained by plotting 
the conductivities obtained against the concentrations. 7 Kohl- 
rausch’s values of the conductivity for various concentrations of 
the same salt were plotted to the same scale on the same co- 
ordinate paper. The ratio of the two conductivities for the same 
concentration gives the factor by which the observed values are 
reduced to the standard employed by Kohlrausch. This ratio 
was found to be practically the same for both electrolytes, 
and in the ease of both, constant throughout my range of 
dilution. 
Bath. 
As the conductivity of a solution varies with the temperature, 
it was necessary to have a bath whose temperature could be kept 
constant for a sufficient time in which to make the measurement. 
Tap water, kept continually stirred by a mechanical stirrer 
driven by a small hydraulic motor, made an excellent bath. A 
thermostat was not found necessary ; for, as the temperature of 
the room was generally near 18° C., the temperature of the bath 
would not change one-fiftieth of a degree in thirty minutes. 
The thermometer used was graduated to a fiftieth, and could 
easily be read to a hundredth, of a degree. This thermometer 
had had its errors determined at the Physikalisch-Technische 
Reichsanstalt, Berlin. 
All solutions were allowed to remain in the bath ten minutes 
at least before observations were taken. After a few minutes 
another observation of the resistance was taken. This was done 
to insure that the solution had taken the temperature of the 
bath. 
Preparation of Simple Solutions. 
The method adopted was to make up a few solutions of 
different concentrations of each salt. These solutions were care- 
2 Kohl u. Hol:, loc. cit., p. 159) tab. 2: 
