296 ON THE CALCULATION OF THE CONDUCTIVITY OF 
and 0.15 per cent at the point farthest from the centre, used in 
my experiments. 
Platinizing the Electrodes. 
The electrodes, after being washed in boiling alkali and acid, 
were placed in a solution prepared from a recipe given by 
Lummer and Kurlbaum, and referred to by Kohlrausch.* This 
solution consists of 1 part platinum chloride, 0008 of acetate 
of lead, and 30 of water. They were then connected with the 
terminals of two Bunsen cells arranged in series, the direction 
of the current being frequently changed. When the electrodes 
had become covered with a velvety coating of platinum black, 
they were removed from the solution and thoroughly washed 
with boiling water to remove all traces vf the chloroplatinic 
acid. The platinizing can be done much more quickly with the 
above solution than with the chloroplatinic acid alone. 
Reduction Factor. 
To find the factor, which would reduce the observed econduc- 
tivities to the standard employed by Kohlrausch, (the eondue- 
tivity of mercury at 0.C), the values of the conductivity for a 
series of solutions of each salt, which were measured for the 
purposes of calculation, were plotted against the concentration 
(gramme-equivalents per litre), and conductivities corresponding 
to the concentrations examined by Kohlrausch, taken off these 
curves and compared with the values given by him. The ratio 
of these values was found to be practically constant for each 
salt through as wide a range of dilution as it was necessary for 
me to measure. 
Temperature. 
All conductivity measurements were made at 18°C. To 
insure this condition, the cell containing the solution to be 
measured was placed in a water-bath, the temperature of which 
was regulated by a thermostat, of the form recommended by 
Ostwald in his Physico-Chemical Measurements, p. 59, fig. 42. 
The regulating liquid, which was water, was enclosed in a brass 
* Wied. Ann., LX (1897), p. 315. 
