BY MIXTURES OF ELECTROLYTES BARNES. 143 



Conductivities were determined by Kohlrausch's method 

 with the alternating current and telephone. The Wheatstone's 

 bridge consisted of four coils, two of which, the 100 and 1000 

 ohms, were the only ones used. These coils were correct at 

 17.5C. and had a temperature coefficient of 0.000267 per centi- 

 grade degree per ohm. The correction for temperature was 

 applied when the observations were made in the basement room 

 referred to below. The platinoid bridge wire was calibrated by 

 the method proposed by l Strouhal and Barus with ten gerrnan 

 silver wires of equal length. A telephone made by Ericsson of 

 Stockholm, and an inductorium made after a plan of Ostwald's 

 anjl giving a clear high note were employed. For a detailed 

 account of the pycnometer, and of the instruments employed in 

 the conductivity observations, with the methods used, see my 

 paper referred to above. 



Three electrolytic cells of two types were used. One, with 

 the shape of a U-tube, was employed for the stronger solutions 

 of the hydrochloric acid. The other two were of the Arrhenius 

 form. One of these, with electrodes at a distance from one 

 another of about \ cm., was used for the weak solutions 

 employed in the determination of the specific molecular conduc- 

 tivities for 0C. ; the other with electrodes at a distance of about 

 5 cm., for the stronger solutions of the two salts. The electrodes 

 were all of stout platinum foil firmly fixed to the platinum wire 

 and glass connections, so that the capacity of the cell once 

 determined would remain the same throughout a series of 

 experiments. These electrodes were platinized in a solution 

 prepared from 2 Lummer and Kurlbaum's recipe. The reduction 

 factor of each of these cells, by which the observed conductivities 

 were reduced to the standard employed by Kohlrausch, was 

 obtained by comparing the values determined for two carefully 

 prepared solutions of potassium chloride, with the values given 

 by 8 Kohlrausch for the same concentrations. Data for the 



1 Wiod. Ann., 10, 326, 1880. 



Wied. Ann., 60, 315, 1897. 



s Kohl. u. Holb., loc. cit., p. 159. tab. 2. 



