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. l 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 case 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 Sim/ile Solutions. 



The method adopted was to make up a few solutions of 

 different concentrations of each salt. These solutions were care- 



1 Kohl. u. Hoi., loc. tit., p. 159, tab. 2. 



