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 
17.5°C. 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 *Strouhal and Barus with ten german 
silver wires of equal length. A telephone made by Ericsson of 
Stockholm, and an inductorium made after a plan of Ostwald’s 
and 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 condue- 
tivities for 0°C. ; the other with electrodes at a distance of about 
5 em., 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 ? 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 *Kohlrausch for the same concentrations. Data for the 
1 Wied. Ann., 10, 326, 1880. 
2 Wied. Ann., 60, 315, 1897. 
3’ Kohl. u. Holb., loc. cit., p. 159, tab. 2. 
