377 



The water used in these experiments was carefully purified by 

 Jones and Mackay's ') method, and collected in wellsteamed resistance 

 glass vessels. Freshly purified water was used in all e.xperiments. 

 The conductivity of the water used varied from 4 X 10-^ (o 

 5 X 10-6 at 0°." 



The measurements were carried out by the alteniatin{>' current- 

 telephone method 'in a closed well platinised cell, with a tiiermo- 

 meter tightly fitting its mouth. In our 

 hot and moist climate, moisture con- 

 denses in the interior of vessels sur- 

 rounded with ice ; so there is the danger 

 of dilution of the solutions in open 

 mouth cells; but this difliculty is removed 

 by having closed vessel for putting in 

 solution. The bath was ofpure melting ice. 



The temperature as indicated by the 

 thermometer was kept constant for 

 nearly half an hour, and then readings 

 were taken. The cell was now taken 

 out of the bath and made to attain the 

 ordinary laboratory temperature, and 

 diluted with calibrated standard pipettes. 



Merck's chemically pure substances were purified by repeated crystal- 

 lisation and dried according to the nature of the substance in question. 



Hydrochloric acid was prepared by dissolving in conductivity 



.--^-^ 



') Zeit. Phys. Uhem. 32, 237, (1897). 



