40 ROYAL SOCIETY OF CANADA 
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 concentration. Data for the determination 
of the reduction factors were available only at 18°, but as the cells were 
of glass their values at 0° would not be practically different from those at 
18° 
The bath in which the cells were placed for the determination of the 
conductivity at 18° C., contained tap water which was kept continually 
stirred by means of a mechanical stirrer driven by one of Henrici’s small 
hot air motors. As the temperature of the room was generally near 18°, 
it was found possible to keep the temperature of the bath within one- 
fiftieth of a degree of the required temperature for thirty minutes. In the 
case of the observations at 0° the bath was modified so that it could be 
kept constantly at this temperature by means of pieces of ice floating in 
it, while the water, which in this case contained a little salt, was kept 
in constant motion. The ice was prevented from coming in contact 
with the cell by placing around the cell a cylindrical screen of wire 
gauze 17 cm. in diameter, and reaching to within 10 cm. of the bottom 
of the bath. By adding or removing pieces of ice, the temperature of the 
bath could be kept constant within one twenty-fifth of a degree, for the 
required time. The measurements of the conductivity at 0° were made in 
a basement room of the college, where the temperature, during the 
months of observation, was generally below 8° C. The thermometers 
used were both graduated to a fiftieth of a centigrade degree, and each 
had had its errors determined. Hach solution was brought to the required 
temperature before it was placed in the cell, and while in the cell succes- 
sive observations of the conductivity were made to insure that the tem- 
perature of the bath had been taken. 
MEASUREMENT OF THE DEPRESSION OF TEE FREEZING POINT. 
The method employed for finding the freezing points of the solutions 
was the same in principle as that described by Loomis.” The size of the 
protection bath was larger, and it was better protected from the influence 
of the surrounding temperature than that employed by Loomis, and the 
stirring was done mechanically. The apparatus is shown in Fig. 1, which 
is taken from a photograph. 
The thermometer used (7' in the figure) was of the Beckmann form, 
and had been tested for calibration error at the Physikalisch-Technische 
Reichsanstalt, Berlin, It was graduated to a hundredth of a degree, and 
could be read to the one four-thousandth of a degree by means of a 

1 Kohl. u. Holb., loc. cit., p. 159, tab. 2. 
2 Phys. Review, 1, 199, 1893, and 9, 257, 1899. 
